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Engineers Ask Nature for Design Advice

December 11, 2001

By JIM ROBBINS




What does a flower known as the sacred white lotus have to
do with house paint?

In the world of biomimicry, everything.

The white lotus
is a symbol of purity, yet it grows in swamps around the
world. The secret of how the flower rises above its dismal
environment was discovered by a German botanist, Dr.
Wilhelm Barthlott at the University of Bonn, who spent 20
years studying the microscopic architecture of thousands of
plant surfaces with a scanning electron microscope. Dr.
Barthlott noticed that the leaves that needed the least
amount of cleaning before they were scanned had the
roughest surfaces.

And the cleanest leaf of all - the white lotus - turned out
to have tiny points on it, like a bed of nails, Dr.
Barthlott found. When a speck of dust or dirt falls on the
leaf, it teeters precariously on those points. When a drop
of water rolls across the tiny points, it picks up the
poorly attached dirt and carries it away.

The lotus, in other words, has a self- cleaning leaf.

The
lotus effect, as it is called, has been applied to a house
paint made in Germany called Lotusan. The paint, on the
market in Europe and Asia, is guaranteed to stay clean for
five years without detergents or sandblasting. Now the
lotus effect is being developed for other products,
including roof shingles and auto paint.

The lotus effect is an example of biomimicry, an
engineering approach that has been gaining momentum in
recent years as manufacturers look to nature to solve some
engineering problems. By looking at the way plants and
animals handle similar kinds of problems, the engineers
hope to make products that are less polluting, use fewer
materials and even cut costs.

"Businesses should work like a living system," said Janine
M. Benyus, a science writer who wrote "Biomimicry,"
published in 1997, and is now a consultant on the subject.
"They should find a way to create conditions conducive to
life, not toxic to life."

Nature has inspired engineers for a long time, for things
like hypodermic needle tips shaped like rattlesnake fangs
and Velcro, which is based on the same principle as those
cockleburs that stick to socks in a walk through a field.
But the search for biological designs with commercial
potential has become more sophisticated and more
widespread.

The examples are legion. Dr. Robert J. Full, a biologist at
the University of California at Berkeley, has discovered
that the attractive force between molecules allows the
gecko, a small lizard, to scamper across ceilings and up
walls at three feet per second.

Microscopic tips of hair on the gecko's feet actually get
close enough to interact with the molecules of the surface
it is crossing. To take another step, the gecko peels each
foot from the wall. The charge is so powerful that,
theoretically, a 90-pound weight could be suspended from a
gecko.

A novel approach to hearing comes from the parasitic Ormia
fly, which is being studied at the State University of New
York at Binghamton and at Cornell. Crickets, able to
disguise their location by how they chirp, cannot fool the
Ormia, which lays its eggs on the cricket and has an ear
that has evolved to find them. Researchers have discovered
that the fly has the biological equivalent of directional
microphones in its ears; they hope that their studies will
lead to a better hearing aid for people.

The idea of biomimicry has become Ms. Benyus's stock in
trade. She travels extensively explaining the concept to
businesses like Interface Carpets and Nike.

She recently returned from a snorkeling trip to the
Galápagos Islands with a group of wastewater treatment
engineers from Carollo Engineering, a California firm. The
engineers went to see organisms that had evolved to solve
their own water treatment problems, like mangrove trees
that turn salt water to fresh water, and filter feeders,
like barnacles, that eat by straining water.

The engineers returned home with food for thought. Pipes at
wastewater plants build up mineral deposits that impede the
flow of water. How, the engineers wondered, do filter
feeders deposit minerals to build a shell and then turn off
the mineralization when it is big enough. If the engineers
can understand that process, they thought, they may be able
to stop the calcium carbonate deposits at treatment plants
and avoid using toxic chemicals to dissolve the deposits.

It is an example of thinking about manufacturing in a
different way. "The question we ask is, How would nature
solve this problem?" said David Oakey of David Oakey
Designs, a company in LaGrange, Ga., that designs
commercial carpeting and other textiles using nature as a
model. "When you ask that question, you move in directions
you never would have thought about."

One such project near the end of development at a
Department of Energy laboratory is a water-resistant glue
made from mussels. Mussels are bivalves that fasten
themselves firmly to ships, piers and other objects in salt
water. The foot of the mussel is equipped with a tiny organ
that excretes something called byssal threads, four
proteins that combine, in the presence of a catalytic fifth
protein, to create the glue. The glue is especially
powerful, adhering even in salt water and working in a many
environmental conditions.

"We've measured bond strength, and there's evidence that it
can be developed into good adhesive," said Dr. Frank
Roberto, a senior scientist at the Department of Energy's
Idaho National Engineering and Environmental Laboratory in
Idaho Falls. Experts are also looking at using the
superglue to fasten the metal oxide platters on computer
hard disks, to replace sutures in the human body and to
repair ships while they remain in the water.

A major hurdle is that 10,000 shucked and ground-up mussels
are needed to distill a single gram of the protein. But
nine years after they began, scientists are manufacturing
small amounts of glue in a fermenting process. But
fermenting will not produce enough glue for commercial use.
One possibility, Dr. Roberto said, is to insert a mussel
gene into a plant through genetic engineering so the
supersticky proteins can be grown as a crop.

Some researchers and entrepreneurs consider splicing genes
a legitimate way to enhance biomimicry. A biotechnology
company in Montreal called Nexia, for example, says that it
has transplanted the gene for making dragline silk from the
golden orb weaving spider into a handful of Nigerian goats
that can now be milked for silk. Re-creating spider silk is
one of the field's major goals because it is five times as
strong as steel and much lighter.

Nexia's chief executive and founder, Dr. Jeffrey Turner,
said the transgenetic goats excreted protein in their milk
that, when isolated, assembled itself into fine strands of
spider silk, a product the company calls Biosteel. The
strands are woven into larger units.

"We hope to have thousands of goats producing silk for
everything from ophthalmic sutures to bulletproof vests,"
said Dr. Turner, who added that the process did not harm
the goats. "A goat has 70,000 genes, and only one of them
is from a spider." But transplanting genes between species
worries some.

"That's about as far from biomimicry as you can get," Ms.
Benyus said. "The movement of genes from a mammal to a
plant is not a common natural strategy. It's really scary
to me."

Some researchers are looking at natural processes of
construction in the hope of finding efficient, less
polluting ways to build structures. At Sandia National
Laboratory in Albuquerque, such work tries to mimic abalone
shells, which are among the hardest, most durable materials
in nature. The shells are made up of alternating layers of
hard and soft material. When a crack occurs in a hard
layer, it is absorbed by the soft layer and does not
spread.

While some packaging mimics that layering, it is still
manufactured with ordinary methods: the energy- intensive,
polluting approach that engineers call "heat, beat and
treat." Dr. Jeffrey Brinker, a senior scientist at Sandia,
has been working with others on ways to create such
materials with self-assembling polymers. That strategy
depends on repellent and attractive forces like the ones
that let detergent molecules in a solution dissolve the oil
in a pan.

Molecules of smart polymers can be herded almost instantly
into hard and soft layers with synthesized detergent
molecules to create things as diverse as hard, transparent
finishes on automobiles and coatings for windshields. The
process is now used commercially to make parts for
computers, and it may soon find wider application.

"They're more elegant and more efficient than traditional
polymers," Dr. Brinker said. "They are very cheap, clean
and there is no waste."

Another area where biomimicry may be commercially useful is
in carpet manufacturing. One carpet company that is
interested in a more natural approach is Interface Carpets,
one of the world's largest commercial carpet companies,
based in Atlanta. It went in that direction after its chief
executive, Ray Anderson, read a book by Paul Hawken, Amory
Lovins and L. Hunter Lovins called "Natural Capitalism"
(1999). In Mr. Anderson's own book, "Mid- Course
Correction: Toward a Sustainable Enterprise" (1998), he
called moving toward sustainability the next industrial
revolution.

"I am a plunderer," Mr. Anderson was quoted as saying,
speaking of his business and manufacturing methods, in an
interview in U.S. News & World Report in 1998. "Someday
people like me may be put in jail."

Mr. Oakey's company designs products for Interface. A
biomimicked carpet now on the designed by Mr. Oakey is
called Entropy. When an ordinary commercial carpet wears
out, the whole thing needs to be replaced because of
differences in dye lots, though just 20 percent of the
carpet may be be worn. Entropy, Mr. Oakey said, mimics the
randomness of a forest floor with different shades and
sizes. Because there are no matching problems, small
sections can be replaced, installation is easier, and there
is far less waste.

Entropy is just a start, not an end, Mr. Oakey said.
Interface is doing research on carpets made from a plastic
formed with corn and recycled materials.

Nature continues to lead him to think about carpet in new
ways. "Can you do it without dye, but with refraction, like
the feather of a bird?" he asked. "Can you make it like a
snake skin, where instead of taking out the whole carpet
you take a sliver off the top and replace that?"

http://www.nytimes.com/2001/12/11/science/life/11MIMI.html?ex=1009190728&ei=1&en=ad4f957d002fde58



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